This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Project 1 seeks to improve our capability to quantitate very small samples. These capabilities will use interfaces developed for our new gas-accepting ion source, which, while recently installed onto our existing 1-MV AMS system, has not yet been fully characterized. This source makes more efficient use of the sample and requires less sample handling. It reduces the minimum sample size required for analysis while improving analysis throughput using appropriate interfaces to directly couple standard bioanalytical techniques to AMS. One goal of Project 1 is to develop an on-line combustion interface to our gas-accepting ion source to provide a direct analysis of small, well-defined biochemical samples. While the use of gaseous samples will prove beneficial for many small radiolabeled samples, it may not fulfill all of our requirements for the analysis of DNA and proteins from specific cell types. The relative small size (<100 [unreadable]g C) and low 14C/C enrichment (1-2 Modern) of DNA or protein samples analyzed in bomb-pulse dating requires the use of solid graphite targets. The LLNL designed high-output solid graphite Cs-sputter source and HVEE FN-class tandem electrostatic AMS system at LLNL routinely achieves 15% total system efficiency, so 1% measurement precision of recent biological material is possible with samples containing as little as 10 [unreadable]g C, if these small samples can be reduced to graphite and effectively consumed in the ion source.